In recent years, CTP technique representing the development direction of international advanced printing plate-making omits the conventional photosensitive imaging process and simplifies the plate-making procedure. However, CTP technique still limits to the thinking of photosensitive chemical imaging and still has the problem of pollution from chemical waste liquid in the post-treatment. With the introduction of many compulsory environmental protection standards in the world, the research on environment-friendly CTP technique has become a new hotspot in the frontier field of world's printing industry. Currently, it is reported that the inks as a core material of ink-jet CTP technique include water-soluble ink solution, thermosetting ink, ultraviolet (UV) curing ink, but the produced plate has a printing durability of 10,000 or 20,000 copies, and the imaging quality and the resolution of the printed matter are low. Therefore, developing a high-resolution ECO-solvent ink is a key deciding the direction of CTP plate-making.
Light solvent ink is a popular solvent ink in recent years, the main reasons lie in that it has a faint smell, the ink particles are fine and the images obtained by ink-jet printing are very nice. The greatest feature of a light solvent ink is its environmental friendliness, which is mainly embodied by the decrease of volatile organic compounds (VOC) and the disuse of toxic and harmful organic solvents (such as cyclohexanone and butanone) and eliminating the dependence on the ventilator in light solvent ink workshops. Light solvent ink is very popular in developed countries, while the conventional solvent ink almost has no market in Europe and the United States. Light solvent ink has become an inevitable development trend of the ink industry [Dai Bin and Qiao Xu, Production and Development of Propylene Glycol Ether Ester Series Solvents, Anhui Chemical Industry, 2007, 33, 3, 4-6.]. Light solvent ink is a solvent between the water-based ink and the solvent-based ink, possesses the advantages of the water-based ink and the solvent-based ink and has the features of environmental friendliness, high precision and outdoor weather resistance. However, the dibasic alcohol ether ester type solvent as a main component of light solvent ink has a complex production process and a long production flow, so that the market supply of such solvents is small and their cost is relatively high. The main advantages of the water-based ink are low cost, no pollution and bright printing colors, but since water as its main component has a slow speed of volatilization, the images ink-jet printed with a water-based ink are difficulty dried and absorbed by the medium. As a result, the water-based ink is mainly used on paper and media having a coating with various fibers (cloth) as substrate. Generally, the images formed by a water-based ink are used indoors owing to its poor weather resistance. According to the present invention, an ink with low cost and high environmental performance is prepared by choosing a mixture of water and a specific light solvent as the solvent of the ink, to further lower the toxicity brought about by the light solvent of the ink, and to give consideration to precision and outdoor weather resistance.